The occurrence of fetal and ectopic antigen expression in the serum and liver tissue of carcinogen-treated mice will be determined by immunochemical methods and correlated with the degree of hepatocellular pathology observed. The transformation-associated antigens, alpha-fetoprotein and gamma fetal antigen, will be comparatively evaluated as to their immunodiagnostic potential in a well-defined hepatocarcinogenesis system. Additional experiments, utilizing an in vitro-propagated hepatoma cell line, will address the possibility that the dimethylsulfoxide-induced phenotypic normalization of transformed hepatic cells may have specific antigenic correlates, as reflected in the control of tumor-associated or differentiated gene expressions. Such studies may elucidate specific associations between ectopic antigen expression and the process of neoplastic transformation.